Field of the Invention
The present disclosure relates to a method of starting a fuel cell system for a vehicle and a fuel cell system.
Discussion of the Background
For example, in a solid polymer electrolyte fuel cell, a membrane electrode assembly (MEA) is sandwiched between a pair of separators, the membrane electrode assembly including a polymer electrolyte membrane formed of a polymer ion exchange membrane, and the anode and cathode electrodes that are disposed on the respective sides of the polymer electrolyte membrane. In general, a plurality of fuel cells of this type are stacked together to form a fuel cell stack which is incorporated into an in-vehicle fuel cell system, for example.
Normally, in the fuel cell, a fuel gas passage for supplying a fuel gas to the anode electrode is formed between one separator and the membrane electrode assembly, while an oxidant gas passage for supplying an oxidant gas to the cathode electrode is formed between the other separator and the membrane electrode assembly. In addition a cooling medium passage for cooling the membrane electrode assembly is formed between adjacent separators.
A cooling medium supply unit which supplies a cooling medium to a cooling medium passage includes a pump which circulates the cooling medium, a radiator which reduces the temperature of the cooling medium by using the open air, and an ion removal device (impurity removal device). The ion removal device has a function of removing conductive ions such as metal ions which are eluted to the cooling medium from the radiator, the fuel cell stack, walls for forming passages, and the pump.
In above-mentioned fuel cell system, the pump is stopped when the operation of the fuel cell system is stopped, then the cooling medium is not sent to the ion removal device. Therefore, while the operation of the fuel cell system is stopped, conductive ions are eluted into the cooling medium, and the concentration of the conductive ions in the cooling medium increases.
Thus, for example, in the cooling system for a fuel cell disclosed in Japanese Patent No. 4066361 includes a fuel cell which is cooled by a coolant; a heat exchanger which reduces the temperature of the coolant; a coolant passage which is connected between the fuel cell and the heat exchanger so as to circulate the coolant therebetween; a removal device which removes impurities in the coolant in the coolant passage; a pump which circulates the coolant in the coolant passage through the fuel cell and the removal device; and a circulating unit which circulates the coolant in the coolant passage through the removal device while the operation of the fuel cell is stopped.